1. Field of the Invention
The present invention is related to window blind manufacturing equipment. In particular, the present invention relates to a ladder station support assembly that is a subcomponent of a modular assembly station which is utilized for assembling (i.e., stacking) a plurality of slats for window blind units.
2. Background of the Invention
The automation of window blind construction has been advanced through the development of modular assembly stations for cutting and assembling a plurality of slats for window blind units. One aspect of manufacturing blinds is the process of inserting each slat into a plurality of ladder-string openings. When the slats are stacked, at least two symmetrically placed ladder-strings provide support for the slats as the slats are cradled between the rungs of the ladder-strings. To accomplish this task, the modular assembly stations utilize a ladder-string applicator which typically includes a U-shaped space presenter housing having a plurality of pairs of opposing slat holders or spring clip ledges which are utilized to support the slats once the slats have been inserted into the ladder-string spaces and stacked.
This blind manufacturing process is best illustrated in U.S. Pat. No. 6,003,218 to Schumann et al., entitled “Apparatus For Cutting and Assembling Slats For Window Blind Units”, subject matter of which is incorporated herein by reference. Schumann et al. teaches a modular assembly station for slotting and stringedly assembling a plurality of window blind units. The assembly station includes a ladder-string applicator in a lateral spaced relationship and in alignment to a U-shaped space presenter housing having an entrance chamber for receiving a slat. A conveyor is provided for receiving a slat and laterally advancing it into the entrance chamber and ladder-string applicator. The conveyor includes a pusher that advances the slat through an elongated channel positioned in alignment with the entrance chamber of the U-shaped space presenter housing of the ladder-string applicator. Thereafter, the slat within the channel is longitudinally advanced by the pusher into the entrance chamber. Concurrently, one or more ladder spaces of respectively one or more ladder-strings are presented in the entrance chamber and the slat is positioned within the ladder spaces. Once inserted within the space of the ladder-string, the slat is lifted by raising the elongate channel until the slat passes through opposing holders or spring clip ledges disposed at the top of the U-shaped space presenter housing of the ladder-string applicator. Once passed through the slot holders, the elongated channel is longitudinally extracted from the U-shaped space presenter housing leaving the slot resting on the top of the holders. The elongated channel is then lowered to its original position to await to be reinserted into the entrance chamber again and to await entry of the next slat.
Another existing design for a ladder station support assembly is a U-shaped ladder station support assembly which features a pair of opposing left and right slat holders (see FIGS. 1-6). The pair of opposing left and right slat holders allow the stacking process to be performed by two elongated channels, instead of just one elongated channel as taught in U.S. Pat. No. 6,003,218 to Schumann et al., subject matter of which is incorporated herein by reference. By utilizing two elongated channels, the stacking process may be accomplished or completed twice as fast as compared to using a ladder station support assembly that provides only a pair of opposing left and right slat holders.
A disadvantage to both the U-shaped space presenter housing of the ladder-string applicators taught in U.S. Pat. No. 6,003,218 to Schumann et al. and the known U-shaped ladder support station (see FIGS. 1-6) is that they require routine maintenance. In particular, springs are utilized in conjunction with the opposing slat holders or spring clip ledges to bias the holders or clip ledges outward. Repetitive stacking cycles wear the springs out and the biased force becomes inconsistent as compared to desired specifications. Thus, the aforementioned devices must be periodically refurbished with new springs and other internal parts such as bushings. Each time one of the aforementioned devices has to be refurbished or replaced, the production line has to be stopped, which inhibits productivity. Moreover, the continuous refurbishment of the space presenter adds more expense to the manufacturing process. For a more comprehensive understanding, the prior art U-shaped ladder station support assembly will be discussed in greater detail in the Detailed Description section.
It would be desirable to provide a ladder station support assembly which is more reliable than the aforementioned U-shaped space presenter housings of the ladder-string applicator taught in U.S. Pat. No. 6,003,218 to Schumann et al. and the known U-shaped ladder support station (see FIGS. 1-6). An ideal ladder station support assembly would be inexpensive, have less parts, and require less maintenance. Moreover, it would be desirable to provide a ladder station support assembly which would be more durable and which can withstand more stacking cycles between routine maintenance. Furthermore, an ideal ladder station support assembly would be able to be integrated or retrofit into an existing assembly workstation or incorporated into new designs. Additionally, it would be advantageous to provide a level of articulation and adjustability to the ladder station support assembly that would allow the height of the opposing slat holder be adjusted to accommodate varying production run parameters.